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Mackie 1202 VLZ into Edirol UA-101 - best connectors?

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Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby BillB » Sun Jun 02, 2019 3:49 pm

I am connecting my Mackie 1202 VLZ (1st generation) into an Edirol UA-101 using the UA's front panel balanced inputs. These can be either XLR or TRS jack plugs on both units.

If I use TRS plugs, the levels match nicely. The UA-101 'phone' inputs are described in the manual as -36 - +4 dBu (variable input sensitivity via front-panel knobs).

If I use XLR:
1) The UA-101 gain range is -50 - -10 dBu - so too sensitive to the line outputs of the Mackie - the signal is far too hot.
2) I can apply the 30dB pad to the Mackie outputs, and set the UA-1010 Sensitivity to about 50%. Doing this, the (metered) levels seem to match nicely.

So, to carry on using the TRS, I would need to make up a cable pair of the right length. Not a major hardship. The question is whether it is OK to sue the XLRs I already have at the correct length: is the odd gain staging (-30dB at the Mackie outputs and presumably around +30dB gain at the UA-101 preamps) likely to lead to any issues? I didn't notice any input noise when monitoring on headphones at the UA-101's highest output levels. The disadvantage with the XLR option is the possibility of accidentally engaging 48v phantom power on the UA-101 - any chance of this damaging the Mackie, or is that a non-issue?
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Re: Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby Hugh Robjohns » Sun Jun 02, 2019 4:18 pm

BillB wrote:The question is whether it is OK to [use] the XLRs I already have at the correct length: is the odd gain staging (-30dB at the Mackie outputs and presumably around +30dB gain at the UA-101 preamps) likely to lead to any issues?

I doubt it will make any difference at all. In the majority of cases, the line level inputs on most interfaces simply pad the signal down by 30dB and route into the mic preamp. All you're doing is moving that pad from the interface back into the Mackie desk... so there's actually no practical difference other than a change to the signal level running down the cable... and that's not going to worry anyone in the context of a metre or two of balanced cable in a home studio!

The disadvantage with the XLR option is the possibility of accidentally engaging 48v phantom power on the UA-101 - any chance of this damaging the Mackie, or is that a non-issue?

Not with the mic-level output pad switch engaged on the Mackie. You're quite safe in that configuration!

The 30dB pad reduces the phantom voltage far below the 25V rating of the Mackie's balanced main output drivers' DC-blocking capacitors.

However, without the pad switched in -- so when providing line level into a device providing phantom power -- there is a risk of over-voltage of the output capacitors and that situation should be avoided!

H
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Re: Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby Mike Stranks » Sun Jun 02, 2019 4:31 pm

Hi Bill

As I'm not familiar with the Edirol I've checked-out the manual online just to see how Roland intend you to use the inputs.

According to the manual and in summary:

* The front-panel inputs have a mic preamplifier; the rear panel inputs do not. They're intended for line-level outputs from something like a mixer.
* The front-panel XLR inputs are designed to handle microphone signals and take the input signal and put it through the preamp.
* The front-panel jack sockets are designed for line-level inputs. Although the preamp is still in circuit the the signal is attenuated before it hits the preamp. This technique is common for mic and line inputs on very many prosumer mixers.
* The rear-panel Jack input sockets are designed to take line-level signals and not put them through any additional pre-amplification.

So in answer to your question, personally I'd be using XLR-Jack leads connected to the rear input sockets. Second-best for me would be the same leads connected to the front input jacks.

If you use XLR-XLR leads connected to the front panle sockets you're taking a signal that the Edirol is designed for and putting it into a mic input with a mic preamplifier. Although it may work, that isn't how it's designed to work. As you say, there's also the risk of engaging 48-volt phantom on the Edirol. It may not damage the Mackie mixer, but the mixer will be far from happy and will behave in an odd way. Meters possibly behaving oddly and funny noises-off. To be avoided!

XLR-Jack leads are the way to go. Preferable connected to the back inputs, but to the front ones if that's easier for you.

(Typed before seeing Hugh's response, but left 'up' anyway. My response takes no account of the fact that the Mackie output can be padded-down.)
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Re: Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby BillB » Sun Jun 02, 2019 4:36 pm

Thank you, Hugh and Mike - perfectly clear answers. So it comes down to whether I bother to make TRS cables and thereby remove any risk of ruining the Mackie output capacitors... The Mackie has done me proud for more years than I can remember so deserves a bit of precautionary TLC. I will take the (very slim) risk with the XLRs in the short term, but will add making up the TRS cables to the top of my to do list.
Mike, the rear inputs are already fully occupied, so this was a way of using the two spare front-panel inputs.
Thank you, chaps :thumbup:
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Re: Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby Sam Spoons » Sun Jun 02, 2019 4:56 pm

I've removed the button cap off the pad on my 1202VLZ (mk1 I think, and to prevent it being engaged in my case) and taped over the hole. I can't see a problem doing the same to prevent it being accidentally disengaged.
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Re: Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby BillB » Sun Jun 02, 2019 5:00 pm

Thanks, Sam, removing the functionality is one way, but it goes against my "what if?" grain...
I just need to make (buy :o ) and use the correct cables.
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Re: Mackie 1202 VLZ into Edirol UA-101 - best connectors?

Postby Sam Spoons » Sun Jun 02, 2019 5:22 pm

Yeah, I know where you're coming from. Really I meant as a temporary solution until a 'proper job' could be done. :thumbup:
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